Amateur tip - Make shims out of used plastic food container lids (I know this may be common knowledge, but I thought I'd post anyway.)For the Hobie 17(/18 upgraded) rudders "Molly McButter" bottles are nearly the same sizs as the contact area for the upper castings. The lowers are smaller.I used 2 "I Can't Believe It's Not Butter" lids and made 8 shims.

1) Eat baked potatoes, with all the fixins (especially bacon), and put I Can't Believe It's Not Butter tub lids in the special basket in dish washer (so they dont fly all over and melt onto the heating element).

2) Trace appropriately sized circular object onto lids as many times as you can.

3) Cut shims out with scissors.

4) Punch holes in center for bolt. I used a hole punch and "nibbled" out the hole till it fit.

Cut out pieces of milk jug (1" square, round if you want to be fancy). Jam as many in between the housing and rudder as will fit to be snug. Insert pivot bolt. Use hammer to punch bolt through shims. Install nut onto bolt.

I must be old school. I too make my own shims but from a 12"x12", 1/16" PTFE Sheet (Dupont calls it Teflon). It cost about $25.00 for the sheet, but so far a set of 4 - 2" dia washers,1/side/blade, has lasted me 5 hard years of sailing with no noticeable wear. They work great with virtually no slop in the rudders. Not as cheap and sexy as a Pringles lid, but well worth the price.

P.S. I made 3 washer sets total, and still had half the sheet left which I have used for other projects as well.

Nylon Washers are much more popular now than they used to be also, most hardware stores and big box stores carry them, if not you can get them from mcmastercarr pretty cheap also. We use quite a few of them at work so I use the ones that I pick up off the shop floor.